1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to image encoding and decoding, and more particularly, to an image encoding/decoding method and apparatus, in which the other color component image(s) except for one of a plurality of color component images of an image is predicted from motion estimation information or a reconstructed color component image of the one of the plurality of color component images using correlation among the plurality of color component images, thereby improving encoding efficiency.
2. Description of the Related Art
In general, when an image is captured, the captured original image is in a red, green and blue (RGB) color format. To encode the RGB color format image, the RGB color format image is transformed into a YUV (or YCbCr) color format. Y is a black-white image and has a luminance component, and U (or Cb) and V (or Cr) have color components. Information is uniformly distributed over R, G, and B components in an RGB image, but information is concentrated on a Y component and the amount of information in U (or Cb) and V (or Cr) components is small in a YUV (or YCbCr) image. Thus, the YUV (or YCbCr) image can be compressed with high compression efficiency. To further improve compression efficiency, a YUV (or YCbCr) 4:2:0 image obtained by sampling color components U (or Cb) and V (or Cr) of a YUV (or YCbCr) image at a ratio of 1:4 is generally used.
However, since 1/4 sampling of U (or Cb) and V (or Cr) components in a YUV (or YCbCr) 4:2:0 image causes color distortion, it is not suitable for providing high display quality. Thus, a method for effectively encoding a YUV (or YCbCr) 4:4:4 image without sampling U (or Cb) and V (or Cr) is required. Recently, residual color transform (RCT) which directly encodes an RGB 4:4:4 image to remove color distortion occurring in transformation of an RGB image to a YUV (or YCbCr) image has been suggested.
When an image like a YUV (or YCbCr) 4:4:4 image and an RGB 4:4:4 image in which color components have the same resolution is directly encoded using a related art encoding method, encoding efficiency is degraded. Thus, a method for improving encoding efficiency while maintaining high display quality by prediction based on the statistical characteristics of an image is required for a case where a YUV (or YCbCr) 4:4:4 image is encoded or an RGB image is encoded in an RGB domain without being transformed to a YUV (or YCbCr) format.